BulletSim: remove double application of buoyancy. Centralize computation of buoyancy. Add motor angular debugging controls.
BulletSim: Redo linear function coding so they can better interact. New algorithm for limitMotorUp that relies on going up when not colliding rather than distance from ground. Add parameter for turning on and off embedded source vehicle debugging.
Fix exception reporting in SceneObjectPart so it logs what the exception is rather than just saying it happened.
BulletSim: Add IsSelected attribute to physical objects. Have vehicles check to see if physical before trying to step. Replace vehicle gravity application. Previously relying on Bullet to apply gravity but since vehicles over-ride the velocity calculation, gravity never had a chance to accelerate the body down. Added AddForceImpulse as well as AddForce for those who need to apply immediate velocity updates. Use the impulse to apply the linear motion.
BulletSim: add osGetPhysicsEngineType() LSL function and update
the physics engines to return the name that is specified in the INI
file ("physics = XXX") as the type of engine.
This os function is a little different than the others in that it
does not throw an exception of one is not privilaged to use it.
It merely returns an empty string.
BulletSim: move center of gravity of linkset to its geometric center.
Necessitated allowing simulator and physical position of a body to
get out of sync since Bullet assumes that <0,0,0> is the center of mass.
Update DLLs and SOs for the UpdateChildTransform so positions of
  individual prim in a linkset can be implemented.
BulletSim: disable center-of-mass computation for linksets until debugged. Move physical prim above ground if it is underground. Previously tried to correct by applying and up force but the prim would never go through the ground.
BulletSim: fix not moving physical objects below terrain to over terrain.
Add locking on register prestep action list preventing potential race conditions.
Little comment and formatting changes.